1. Technical Field of the Invention
The present invention relates generally to an isolation valve and, more specifically, to a gate valve for controlling steam flow, wherein the gate valve is equipped with a toothed seat ring to induce vortices within the fluid flow for suppressing acoustic resonance.
2. Description of the Related Art
Gate valves are typically used to shut off fluid flows. Fluids flowing through the open valve may be liquid or gaseous. Gate valves typically consist of a valve body defining a fluid passageway, two valve seats with one being located on the upstream side of the valve and the other being located on the downstream side of the valve, and a system of shut off plates which generally move in an axial direction perpendicular to the fluid flow to shut off the fluid flow. The plates typically engage with the seat to form a fluid tight shut off. The valve is generally opened by retracting the plates away from the seat and out of the fluid flow. In an open position, the plates are typically completely moved out of the fluid flow.
When the gate valve is in the open position, fluid may be flowing at a high velocity through the valve. Due to the nature of its design, acoustic resonance may occur in the side cavities of the valve, which may cause pressure pulsations in the cavities. The acoustic resonance may be excited by shear layer instability at the gaps between the seats and between the seats and the disks. This phenomenon includes the periodic formation of vorticies, which travel across the gap and impinge on the trailing edge of the side branch cavity, therefore generating a pressure pulsation.
These pressure pulsations may excite pressure pulsations in the piping, which in turn may produce vibrations within the structural components defining the fluid flow system (i.e., pipes, fittings, valves, connectors, etc.), which over time, may weaken the structural integrity of the system. For instance, the acoustic resonance may cause a crack to develop within the pipe wall.
Another drawback associated with acoustic resonance is the sound associated therewith. The sound may not only be an annoyance and safety hazard to those working at the nuclear power plant, but may also interfere with the operation of the plant (i.e., the noise may make it difficult for workers to communicate).
As is apparent from the foregoing, there is a need in the art for a fluid control device configured to attenuate resonance generated within a fluid system. These, as well as other features and advantages of the present invention will be described in more detail below.